The present invention relates to devices for cleaning tanks of fluids, and in particular, to devices for cleaning swimming pools. More particularly, the present invention relates to fluid suction or vacuum systems for cleaning swimming pools, and even more particularly, to a device for maintaining contact pressure on a vacuum cleaning head against the floor of a swimming pool.
Vacuum swimming pool cleaning devices are well known. In the typical application, a vacuum swimming pool cleaning head comprises a hollow fixture with an open bottom enclosing a space which may include cleaning or brush elements and which is connected to a suction or vacuum hose providing suction from the swimming pool filter pump. The suction hose draws liquid away from the head and any dirt particles and debris away from the head to the filter as the cleaning head is moved across the pool floor.
A common problem with such vacuum cleaning heads is that there is a tendency for the head to rise from the floor of the swimming pool, despite the application of vacuum by the filter pump. This occurs sometimes when the user moves the head, for example. This can cause dirt particles to be disturbed near the head and accordingly, not to be sucked up by the suction applied by the filter pump.
There are a number of liquid pool cleaning devices which have been developed for assisting in maintaining contact pressure. For example, U.S. Pat. No. 4,783,868 to O'Callahan shows such a device which is provided at the head of a brush. It uses a pivoting vane that applies pressure during forward motion and then pivots to a nonimpeding position upon backward motion. Although this device is useful for pool cleaning brushes, it is not useful for vacuum heads because the vane is located too close to the vacuum head and accordingly will create fluid dynamics which will cause dirt particles and debris on the pool floor to be moved prior to their being vacuumed by the vacuum head. Further, this device shows a device which only increases contact pressure in a forward motion and provides a non-impeding position on a backward motion. With vacuum cleaning of pools, it is common to vacuum in both forward and backward directions. Accordingly, this device would not provide additional contact pressure when moving in a backward direction. A similar device is shown in U.S. Pat. No. 4,733,427 to Conrad. It suffers from the same problem.
Another device is shown in U.S. Pat. No. 4,637,087 to Feinberg. This device uses flaps to allow contact pressure to be provided in one direction and then act as a check valve in the second direction so as to avoid providing contact pressure. Further, this device is provided to clean the walls of swimming pools and not the bottoms. This device also would not be adaptable to a vacuum cleaning head because the water foil thereof is attached too close to the brush head and thus could disturb debris and further, provides for only increasing the contact pressure in one direction only.
Other patents of interest include U.S. Pat. No. 4,742,592 to Addona, Sr. which is also a wall scrubbing device and has some as the same disadvantages of the prior art discussed above. Also see U.S. Pat. Nos. 5,539,947 and 4,766,053 which disclose hydrofoils for vacuum cleaner heads. However, the '053 patent provides for downward thrust only during the pulling stroke. The device of the '947 patent provides downward thrust during both pulling and pushing strokes but in this device, as in the device of the '053 patent, the hydrofoil is mounted on the vacuum cleaning head itself and can create fluid dynamics which would interfere with proper cleaning by disturbing debris on the pool floor.